The purpose of this study is to describe the factors that allow for the survival of patients with persistent truncus arteriosus until adult life and cared for at the National Institute of Cardiology "Ignacio Chávez". From May 2003 to June 2007, six adult patients with clinical suspicion of truncus arteriosus were studied. All patients were subjected to clinical history, electrocardiogram of twelve leads, echocardiography, and cardiac catheterism. In these patients, the clinical symptoms began early of life. The ecocardiographic findings demonstrated the presence of truncus arteriosus type I in all cases and the most frequent associated anomalies were: hypoplasia of pulmonary branches, isolated coronary ostium, persistent ductus arteriosus and right aortic arch. Almost all patients had pulmonary hypertension. Based on this work, we conclude that until now we do not known the actual survival time of adult patients with complex congenital heart disease, such as truncus arteriosus. There are factors, such as pulmonary hypertension and hypoplasia of the pulmonary branches that are deleterious for life in some cardiovascular diseases, but in others allow for the survival of patients, as occurred in these patients with truncus arteriosus.